Method of imparting durable mildew resistance to fibrous cellulose materials



Patented Oct. 10, 1950 METHOD OF IMPARTIN G DURABLE DIILDEW RESISTANCE TFIBROUS CELLULOSE MATERIALS Florence M. Ford and William P. Hall,Wilmington, Del., assignors to Joseph Bancroft & Sons 00., Wilmington,Del., a corporation of Delaware No Drawing. Application April 2, 1948,Serial No. 18,724

This invention relates to the imparting of durable mildew resistance tofibrous cellulose materials.

Cellulose materials such as textile fabrics, are subject to attack byfungi, particularly in certain localities, which causes seriousdegradation of and alteration in the cellulose, resulting in undesirablechanges in appearance and physical characteristics, primarily 'in a verymarked loss in tensile strength. This phenomenon is usually referred toas mildewing and is responsible for the rapid destruction of textilefabrics in many portions of the world.

We have discovered that if acid be chemically combined with cellulose inthe dry state to produce an acid-cellulose complex, the fabric or otherfibrous material is not only rendered midew resistant but the finish isdurable to water and will withstand weathering for long periods of time.Moreover, this result can be obtained through the use of relativelysmall quantities of acid so that tendering of the fabric issubstantially avoided and the fabric in very large part retains itsoriginal strength. The finish also does not interfere with otherfinishes, such as waterproofing, which are frequently employed in thetextile field. It aso does not interfere with dyeing and is veryeffective on dyed goods.

As illustrative of the invention, we prepare an aqueous solution of anacid, such as orthophosphoric, impregnate the fabric with said solution,preferably with a 100% solution pick-up by weight of the fabric in thedry state, after which the fabric is dried and then baked or cured atelevated temperatures, i. e., from 300 F. to 400 F. for a .period oftime ranging from 30 minutes to 2-minutes, in an oven to bring about thechemical reaction between the acid and the cellulose. The drying and thebaking may be performed as a single step, but it is preferable to firstdry the material employing conventional drying temperatures. Byproceedingin this fashion there is less likelihood of tendering of thefabric.

Similarly, to avoid tendering as much as possible, it is desirable toincorporate in the solution a nitrogen containing organic base solublein acid solution and basic therein, as a buffering agent, such, forexample, as urea, which competes with the cellulose for the acid butwhich does not prevent the chemical combination between the acid and thecellulose during the baking. The ratio of carbon to nitrogen in the baseshould not be higher than 2 to l. The reason that it is desirable toincorporate such a buffering agent is that mass action is involved andmore acid must 3 Claims. (c1. 8-1162) be applied to the fabrc than isrepresented by the amount of base element of the acid (or the amount ofacid in terms of base element of the acid) combined in the finished,washed fabric. The presence of such a buffering agent in the solutiontends to avoid tendering during the drying operation. Some nitrogen maybe carried into the complex by the acid, but the presence of nitrogen inthe final complex is of no importance in obtaining the mildewresistance.

The mildew resistance is obtained by the replacement of hydroxyl groupsin the cellulose by acid groups.

The concentration of the solution itself is not critical, as the neededamount of acid to secure the desired degree of mildew resistance may beapplied to the fabric by several impregnations of a dilute solution. Weprefer, however, to use a concentration which will result in theapplication of the desired amount of acid by a single application of thesolution with solution pick-up on the weight of the fabric in the drystate, and in all of the examples hereinafter given a 100% solutionpick-up by weight of the dry fabric is employed. Parts are by weight.

As illustrative of the practice of the invention, undyed cotton clothwas impregnated with the following solution:

300 parts orthophosphoric acid (75%) 600 parts urea 4100 parts waterPounds Warp strength treated fabric before burial Warp strength treatedfabric after burial 121 Warp strength untreated fabric after burial (tooweak to measure) 0 The strength tests were conducted on a regular Scotttester, using 1 inch x 3 inch test samples.

These results show the protective action afforded by the process withthis acid, with a ratio of acid groups to pyranose units of 1 to 20inthe 3 finished, i. e., the washed, dried fabric, or .96%

I phosphorus.

Cotton cloth was impregnated with the same solution and the sameprocedure was followed, with the exception that the temperature employedfor curing was 300 F. and the time minutes.

The results obtained were substantially the same as those obtained inthe first example.

Cotton fabric was impregnated with the same solution and the sameprocedure followed, with the exception that in this instance thetemperature of curing was 400 F. and th time 2 minutes.

Substantially the same results were obtained as in the first example.

In the aforesaid examples, the base element of the acid, i. e.,phosphorus, is present in the finished, i. e., washed and dried fabric,the ratio thereof in terms of acid to pyranose units being 1 to 20, Thisratio gives very effective mildew resistance and is about as high aratio as should be employed when using an acid substantially as strongas orthophosphoric acid.

If a less degree of mildew resistance is desired, the amount of acid maybe reduced.

Thus, for example, a cotton fabric was impregnated with the followingsolution:

100 parts orthophosphoric acid (75 300 parts urea 41,600 parts water byweight and the same procedure was followed as before, with a curingtemperature of 350 F. and a time of 8 minutes. In the washed driedfabric the ratio of phosphorus in terms of acid to pyranose units wasabout 1 to 600 or .0294% phosphorus. With this ratio appreciable mildewresistance was obtained but not as good as obtained in the previouslymentioned examples. With orthophosphoric acid, this is about as low aratio as should be employed.

With such ranges, the amount of orthophosphoric acid applied to thematerial will range from .2% to 4.5% by weight of the material in thedry state, having in mind also the particular temperature and timewithin the temperature time ranges given.

As to the pH of the solution, the initial pH thereof is unimportant solong as the pH on the cured cloth comes down during the curing andbefore washing to from 2 pH to '7 pH as determined by indicatorsolutions. The reaction between the acid and the cellulose occurs onlyunder acidic conditions. Urea is a relatively weak base, i. e., changein the amount thereof has no pronounced effect on the pH of thesolution. During the curing certain reactions take place which cause thepH to fall within the range above indicated. In fact the pH of thesolution may even be on the alkaline side so long as the pH comes downduring the curing due to the reactions occurring during the curing, Thepreferred pH on the cured cloth before Washing is from 3 to 6 pH asdetermined by indicator solutions. The urea may be used in amountsranging from 1 mol to 10 mols of urea to 1 mol of acid, the preferredrange being 1 mol to 4 mols to 1 mol of acid.

In place of the phosphoric acid, other acids may be equally wellsubstituted, such, for example, as metaphosphoric acid, pyrophosphoricacid, ortho, metaand pyrophosphorus acids, phosphamic acid,phosphotungstic acid, sulfuric acid, sulfamic acid, phytic, and similarrelatively strongly effective acids. Also weaker acids may be used, suchas tartaric, lactic, maleic, malic, malonic, phthalic, citric, succlnic,pyroantimonic, dehydroxydiphenic, molybdic, tungstic, vanadic, telluric,selenic, salicyclic, fluosilicic, benzoic and nitric. In fact anysoluble acid, organic or inorganic, substantially non-volatile, whichwill react with the cellulose to replace hydroxyl groups under thetemperature and time ranges hereinbefore stated is suitable. Since thereis a variation in effectiveness, this must be taken into considerationand an amount of acid should be employed which gives an effect at leastsubstantially equivalent to that obtained in the case of orthophosphoricacid with a ratio ranging from 1 to 20 to 1 to 600 of acid to pyranoseunits in the finished fabric after washing and drying.

Metal salts and organic substituted salts of the acids having freeacidity, for combination with the cellulose may also be employed. Theexcess acidity may be temporarily neutralized by means of a basevolatile during curing, such, for example, as ammonium hydroxide.

In fact many substituted acids are very effective as the substituentsmay have anti-fungus properties which enhance the effect of the acidcombined with the cellulose, being carried into the complex by the acid,When substituting these for orthophosphoric acid, the amount employedshould be at least sufiicient to give equivalent effects oforthophosphoric acid when employed alone.

Many suitable organic compounds may be attached to the acids bysubstitution, such, for example, as phenyl, phenol, cresol, bromocresol,dihydroxyhexachlorodiphenylmethane, chlorophenyl, chlorophenol,B-naphthol, chloronaphthalene, dihydroxydichlorodiphenylmethane,alkylphenols, dichlorodiphenyltrichloromethane, naphthalene,alkylnaphthalene, thymol, chlorothymol, xylene, chloroxylene,O-phenylphenol, chloro-o-phenylphenol, toluol, chlorotoluol,anthraquinone, chloroanthraquinone, and hydroxyanthraquinone.

It will be seen that these listed compounds or groups are of a ringstructure and contain one or more rings in their constitution and may,therefore, be classified as carbocyclic compounds. Chlorine, fluorine,bromine and iodine may also be introduced into said compounds, therebyincreasing the mildew resistance in the substituting material.

In using the compounds just mentioned it is sometimes advantageous toattach more than one acid group to the same mildew resistant groups. Forexample, phenol disulfonic acid, Z-naphthol- 6,8-disulfonic acid,anthraquinone-1,5-disulphonic acid, and phenyl diphosphoric acid, may beused. In the case of the dior polysulfonic acids, polybasic propertiesare introduced into the compound by the use of two or more acid groups,and this, as will be further explained, is very beneficial.

The use of' monobasic acids is not practical unless the substitutionleaves a. free reactive acid hydrogen to react with the cellulose andthe required reactions, therefore, will take place. To illustrate,substitution in nitric acid, as, for example, nitrobenzene, will notproduce a compound capable of reactingwith the cellulose as there is nofree acid group available.

Quaternary ammonium compounds, especially those containing aromaticgroups, and hydroxyl chloro or bromo substituted aromatic groups, havegood mildew-preventing properties. These basic compounds, whensubstituted in the aforementioned acids, as, for example, inorthophosphoric acid, may be used with success, as, for example,lauryldimethylphenol ammonium acid phosphate,alphaalphagammagammatetramethylbutylphenoxyethoxyethyldimethylbenzylammonium acid phosphate and dimethyllauryl benzyl ammonium acidphosphate, the substituted phosphoric acid in these cases combining withthe cellulose under the conditions of the process givelement, in theform of a salt, an oxide or hydroxide, is added to the impregnatingsolution. The salt of the inorganic element ma be of a Weak acid notsubstantially reactive with the cellulose, such as, for example, aceticor it maybe of a strong acid capable of reacting with the cellulose,such as orthophosphoric. In the latter case the acid introduced by thesalt into the solution should replace a corresponding quantity of acidin the solution formula. In the former case,

the acid introduced with the salt does not react I with cellulose andthe regular quantity of reactive acid must be used. In case an insolubleprecipitate is formed in solution between the basic element and theacid, the method is not practical without steps being taken tosolubilize the insoluble salt. With a salt such, for example, as copperphosphate, excess ammonium may be used with advantage to obtain a clearsolution for impregnation.

Mildew resistant organic groups may also be introduced into the acidthrough an inorganic element, for example, phenylmercuric acidphosphate, and phenyl cadmium acid phosphate may be used under theconditions described above.

The acid employed which, in addition to being active enough to combinewith the cellulose under the conditions of the process, should not beexcessively volatile during processing, should preferably be soluble inthe solution, and should not detrimentally alter the physicalcharacteristics of the substituted mildew resistant compounds and shouldpreferably show good durability toward water. v

The enhancing mildew resistant substance or substances may be introducedthrough the basic or buffering material, instead of directly through theacid. To this end, in addition to the presence in the solution of thebase as such, the substituted base is added. This ordinarily is not aseconomical. It is to be understood that where the mildew resistantsubstance is introduced with the buffering material, it is neverthelessstill carried to some extent into the complex by the acid.

When the mildew resistant groups are to be attached to base material, itis preferable to attach them to a strong base because the strongbaseusually tends to attach itself more. readily to the acid. Thesu'bstituent group or groups must not be such as to alter the basicproperties of the base to such an extent that its function as 9. baseduring the curing will be destroyed or excessively altered.

The amount of buffering base should be at least such as to secureadequate buffering of the acid. When used in the quantities giving thepH values hereinafter set forth, satisfactory results are obtained.

For the urea other organic buffering agents of the character describedmay be employed, such, for example, as biuret, acetamide, dicyandiamide,guanyl urea, amino-guanidine, biguanide, guanidine carbonate,oxalamidine, carbohydrazidine, and the like. Where strong bases are usedthey should be used in combination with weak bases, such, for example,as urea, and guanidine, for the reason that the initial pH of thesolution presents no particular difficulty where a combination of strongand weak bases is employed, whereas if only strong bases are employedthen it is necessary to very carefully control the pH of the solution soas to ensure its being on the acidic side during the curing.Non-metallic salts of the base may be employed. Substituted bases may beemployed.

The general requirements of the buffering base are that it should besoluble, free of metal, basic toward the acid, and non-volatile underthe curing conditions.

Generally speaking, the lower the temperature of curing the longer thetime and vice versa. Similarly, the lower the acid concentration in thesolution the higher should be the temperature and in some cases, thelonger the time. The preferred temperature is from 340 F. to 375 F. andthe time from 8 to 4 minutes.

In the following examples a single application of solution with roughlya solution pickup by weight on the dry material was employed, with allparts by weight.

Enample I A scoured and dyed cotton fabric was impregnated with thefollowing mixture:

375.0 parts phosphotungstic acid 330.0 parts urea 250.0 parts watersqueezed, dried, aged 15 minutes at 340 F., washed thoroughly inrunningwater 180-190 R, and finally dried.

The treated fabric and a piece of untreated similar fabric were buriedin the soil for 8 weeks to test the resistance to deterioration, thelatter being determined by measuring the tensile strength retention ofthe treated fabric as compared with the fabric strength before burialand with the fabric strength of the untreated fabric after burial. Theuntreated sample test also serves as a guarantee that the soil containedin gredients causing cellulose deterioration.

The tensile strength tests were as follows:

, Pounds Warp strength treated fabric before buriaL- Warp strengthtreated fabric after buria.l 127 Warp strength untreated fabric afterburial (too weak to measure) 0 tained in this example. Substantialresistance can be obtained with even a much lower ratio as will appearhereinafter.

Example II A scoured and dyed cotton fabric was padded with thefollowing mixture:

290.0 parts telluric acid 440.0 parts urea 1000.0 parts water followedby drying, curing 30 minutes at 340 F., washing thoroughly in hot waterand finally drying The treated fabric and a piece of untreated samplewere buried in the soil for 8-weeks and the following tensile strengthretention tests obtained.

Pounds Warp strength treated fabric before burial 119 Warp strengthtreated fabric after burial 51 Warp strength untreated fabric afterburial Example I I I A desized, scoured, mercerized and dyed fabric wastreated as in Example I, curing being done minutes at 350 F. Theimpregnating mixture consisted of 720.0 parts molybdic acid anhydride1320.0 parts urea 1000.0 parts ammonium hydroxide (28%) 500.0 partswater The treated and untreated fabrics were soil buried for 8 weeks andthe following tensile strength tests obtained:

Pounds Warp strength treated fabric before burial 138 Warp strengthtreated fabric after burial 69 Warp strength untreated fabric afterburial 0 Example IV A pure cotton fabric was padded through thefollowing mixture:

450.0 parts lactic acid 1320.0 parts urea 1000.0 parts water dried, aged5 minutes at 340 F., washed 15 minutes in hot running water (ISO-190 F.)and flnally dried.

Treated and untreated fabrics were soil buried for 8 weeks and thentested for tensile strength. The following results were obtained:

Pounds Warp strength treated fabric before burial 135 Warp strengthtreated fabric after burial 98 Warp strength untreated fabric afterburial- 0 Example V A pure dyed cotton fabric was treated as describedin Example IV, the mixture consisting of:

74.0 parts acid phthalic anhydride 125.0 parts alcohol 132.0 parts ureaTreated and untreated cloths were buried for 8 weeks and the followingtensile strength tests obtained:

' Pounds Warp strength treated fabric before burial 128 Warp strengthtreated fabric after burial 90 Warp strength untreated fabric afterburial '0 Example VI A pure dyed cotton fabric was treated as describedin Example IV, the impregnating mixture consisting of:

75.0 parts tartaric acid 132.0 parts urea 100.0 parts water Treated anduntreated fabrics were soil buried for 8 weeks and the following tensilestrength results obtained:

Pounds Warp strength treated fabric before burial 129 Warp strengthtreated fabric after burial 61 Warp strength untreated fabric afterburial 0 Example VII A pure dyed cotton fabric was treated as describedin Example IV. The mixture had the following composition:

130.0 parts citric acid 132.0 parts urea 100.0 parts water Treated anduntreated cloths were soil buried for 8 weeks and the following tensilestrengths obtained:

Pounds Warp strength treated fabric before burial 126 Warp strengthtreated fabric after burial 76 Warp strength untreated fabric afterburial 0 Example VIII Cotton fabric was treated as described in ExampleIV, the padding solution consisting of:

125.0 parts tungstic acid 1320 parts urea .1000 parts ammonium hydroxide300.0 parts water A similar fabric was padded with the above mixture,dried but not aged. It was then washed 15 minutes in hot water (180-190F.) and dried.

The two treated fabrics and an untreated fabric were subjected to theChaetomium test as described in U. S. Quartermaster Corps SpecificationP. Q. D. 447A and the following tensile strength tests obtained:

- thoroughly in running water 180190 F.

This example shows the durability obtained by the aging treatment.

Example IX A scoured and dyed cotton was padded, using the followingimpregnating mixture:

33 parts dicyandiamide 50 parts orthophosphoric acid 750 parts water 56parts formamide 7 parts guanidine carbonate squeezed, dried, aged 7minutes at 330 F., washed and finally dried.

9 Treated and untreated fabrics were soil buried for 8 weeks and thentested:

. Pounds Warp strength treated fabric before burial 137 Warp strengthtreated fabric after burial 120 Warp strength untreated fabric afterburial Example X A scoured and dyed cotton fabric was padded. using thefollowing impregnating mixture:

15 parts phosphotungstic acid 3000 parts water 30 parts urea squeezed,dried, aged 15 minutes at 340 F., washed thoroughly in running water180-190 F. and finally dried.

The cloth contained .17% phosphotungstic acid or 1 acid group to every10,600 pyranose units (average of five tests).

Treated and untreated fabrics were subjected to the Chaetomium test asdescribed in U. S. Quartermaster Corps Specification P. Q. D. 447A andthe following tensile strength tests obtained:

Pounds Warp strength treated fabric before test 113 Warp strengthtreated fabric after test 107 Warp strength untreated fabric after test0 Example XI A cotton fabric was treated as described in Example IV withthe following mixture:

50.0 parts sulfuric acid (con.) 132.0 parts urea 350.0 parts Water Atreated fabric and an untreated fabric were soil buried for 8 weeks andthen tested for tensile strength.

Pounds Warp strength of treated fabric before burial 120 Warp strengthof treated fabric after burial 108 Warp strength of untreated fabricafter burial 0 Example XII A sample of pure hemlock wood pulp wasimpregnated with the following mixture:

65 parts orthophosphoric acid (75%) 132 parts urea 5200 parts waterfollowed by drying, curing minutes at 340 F., washed well in hot water,filtered :and dried.

Samples of treated and untreated pulp were given the Chaetomium test.The untreated pulp showed heavy fungus growth while the treated pulpremained unaffected.

Example XIII A piece of pure dyed viscose rayon fabricwas impregnatedwith the following mixture:

66 parts orthophosphoric acid (75%) 132 parts urea 1100 parts waterdried, aged 5 minutes at 340 F., washed 15 minutes in hotrunning water(180-190 F.) and finally dried.

10 .5, Treatgd and untreated fabrics wr soil buried for 8 we ks and thentested:

' Pounds Warp strength treated fabric before burial Warp strengthtreated fabric after burial 86 Warp strength untreated fabric afterburials. 0

Example XIV A scoured, mercerized and bleached cotton fabric wasimpregnated with the following mixture:

280.0 parts naphtha thiophosphonic acid 330.0 parts urea 1000.0 partswater Pounds Warp strength treated fabric before burial 136 Warpstrength treated fabric after burial--- 96 Warp strength untreatedfabric after burial 0 Example XV A dyed cotton fabric was impregnatedwith the following padding mixture:

16 parts copper oxide 52 parts orthophosphoric acid (75%) 42 partsammonium hydroxide 100 parts urea 1030 parts water dried, aged 5 minutesat 340 F., washed 15 minutes in hot running water (-190" F'.) andfinally dried.

Treated and untreated fabrics were subjected to the Chaetomium test asdescribed in U. S. Quartermaster Corps Specification P. Q. D. 447A andthe following tensile strength tests obtained:

I 7 Pounds Warp strength treated fabric before test 104 Warp strengthtreated fabric after test 103 Warp strength untreated fabric after test0 Example XVI A cotton fabric was impregnated with the following sizingmixture:

49 parts phenol-disulfonic acid 810 parts water 200 parts urea 82 partsguanidine carbonate dried, aged 5 minutes at 340 F., washed 15 minutesin hot running water (180-190 F.) and finally dried.

Treated and untreated fabrics were tested as described in Example XV.The following results were obtained:

Pounds Warp strength treated fabric before test 107 Warp strengthtreated fabricafter test 106 Warp strength untreated fabric after test 011 Example XVII A cotton fabric was padded with the following mixture40.0 'parts phenyl phosphonic acid 66.0 parts urea 200.0 parts waterdried, aged 10 minutes at 340 F., washed 15 minutes in hot running water(180-190 F.) and dried.

Treated and untreated fabrics were soil buried for 8 weeks and thentested:

Pounds Warp strength treated fabric before burial 135 Warp strengthtreated fabric after burial 121 Warp strength untreated fabric afterburial- Example XVIII A cotton fabric was impregnated with the followingmixture;

100.0 parts orthophosphoric acid (75%) 65.0 parts dicyandiamide 150.0parts urea 28.0 parts phenylbiguanide 1869.0 parts water Example XIX Acotton fabric was impregnated with the following mixture:

53.0 parts orthophosphoric acid (75%) 81.0 parts urea 65.0 partsphenyl-guanidine carbonate 800.0 parts water dried, aged minutes at 340F., washed 15 minutes in hot running water (ISO-190 F.) and finallydried.

Treated and untreated fabrics were soil buried for 8 weeks and thefollowing results obtained:

Pounds Warp strength treated fabric before burial 139 Warp strengthtreated fabric after burial 88 Warp strength untreated fabric afterburial 0 Example XX A cotton fabric was padded with the followingmixture:

65.0 parts orthophosphoric acid (75%) 132.0 parts urea 27.0 partschromium fluoride 5200.0 parts water dried, aged 5 minutes at 340 F..washed 15 minutes in hot running water (180-190 F.) and final- .lydried.

Treated and untreated fabrics were subjected to the Chaetomium test asdescribed in U. S. Quartermaster Corps Specification P. Q. D. 447A andthe following tensile strength tests obtained:

' Pounds Warp strength treated fabric before test 110 Warp strengthtreated fabric after test 112 Warp strength untreated fabric after tet-= .2

, 12 Example XXI Tetra-chloro-phenyl phosphoric acid was prepared byflrst reacting together tetra-chlorophenol, phosphorous oxychloride andmagnesium chloride and then vacuum distilling,

A cotton fabric was padded through the following mixture:

50.0 parts of the above distillate 50.0 parts urea 150.0 parts aceticacid dried, aged 10 minutes at 330 F., washed 15 minutes in running hotwater (180-190 F.) and dried.

Treated and untreated fabrics were tested as described in Example XX andthe following results obtained:

Pounds Warp strength treated fabric before test 115 Warp strengthtreated fabric after test 115 Warp strength untreated fabric after test"22 Example XXII A scoured and dyed cotton fabric was impregnated withthe following mixture:

20 parts phenyl phosphoric ac d 25 parts phenol disulfonic acid 200parts urea 50 parts guanidine carbonate 800 parts water dried, aged 24minutes at 300 F., washed 15 minutes in hot running water (180-190" F.)and finally dried.

Treated and untreated fabrics were soil buried for 8 weeks and thentested:

Pounds Warp strength treated fabric before burial 102 Warp strengthtreated fabric after burial 90 Warp strength untreated fabric afterburial 0 Example XXIII A piece of viscose rayon fabric was impregnatedwith the following mixture:

50 parts anhydrous monofiuorophosphoric acid 132 parts urea 3100 partswater dried, aged 5 minutes at 340 F., washed 15 minutes in hot runningwater (180-190 F.) and finally dried.

Treated and untreated fabrics were soil buried for 8 weeks and thentested:

Pounds Warp strength treated fabric before burial 90 Warp strengthtreated fabric after buria1 85 Warpstrength untreated fabric afterburial 0 Example XXIV A sample of pure washed wood pulp was impregnatedwith the following mixture:

65.0 parts orthophosphoric acid 132.0 parts urea 27.0 parts chromiumfluoride 5200.0 parts water followed by drying, curing 10 minutes at 330F'., washed well in hot water, filtered and dried.

Samples of treated and untreated pulp were given the Chaetomium test.The untreated pulp showed heavy fungus growth while the treated pulpremained unaffected.

13 Example XXV A cotton fabric was treated as described in ExampleXVIII, the sizing mixture consisting of:

200 parts salicylic acid 400 parts urea 50 parts cyanoacetamlde 2000parts water Treated and untreated fabrics were tested as described inExample XXII. The following results were obtained:

Pounds Warp strength treated fabric before test 98 Warp strength treatedfabric after test 97 Warp strength untreated fabric after test"- Thetreated cloth gave a test for salicylic acid grouping. When the samemixture was applied and the cloth was dried and washed but not cured,the resulting fabric failed to give a test for salicylic acid, showingthat no combination with the fabric is obtained in the latter case.

Example XXVI A cotton fabric was treated as described in Example XVIII,the si'lng mixture consisting of:

500 parts mon-ofiuorophosphoric acid 640 parts guanidine carbonate 1500parts water The cloth contained 2.5% monofluorophosphoric acid, or 1acid group to every 25 pyrancse units.

Treated and untreated fabrics were soil buried for 8 weeks and thentested:

- Pounds Warp strength treated fabric before burial 116 Warp strengthtreated fabric after burial 110 Warp strength untreated fabric afterburial 0 Example XXVII A cotton fabric was treated as described inExample XVIII, the sizing mixture consisting of:

500 parts tetrachlorophthalic anhydride 1000 parts urea 1000 partsammonium hydroxide solution Treated and untreated fabrics were buriedfor 8 weeks and then tested.

Pounds Warp strength treated fabric before burial 120 Warp strengthtreated fabric after burial 108 Warp strength untreated fabric afterburial 0 The fabric contained 3.1% combined tetrachlorophthalicanhydride or 1 anhydride group -to 55 pyrancse units.

Example XXVIII A pure undyed cotton fabric was treated as described inExample XVIII, using:

parts monocopper phosphotungstic acid 30 parts urea 3300 part water Thecloth contained 0.1 monocopperphosphotungstic 'acid, equivalent to0.002% phosphorus or 1 acid group to every 18,520 pyranose units.

Treated and untreated fabrics were soil buried for 8 weeks and thentested.

Pounds Warp strength treated fabric before burial 145 Warp strengthtreated fabric after burial 118 Warp strength untreated fabric afterburial- 0 Example XXIX 130 parts dicyandiamide 200 parts orthophosphoricacid (75%) 200 parts water, heat to 108 C.

300 parts urea 28 parts guanidine carbonate 40,000 parts water Padded onpure cotton herringbone twill. Dried, cured 5 minutes at 340 F., washedand dried.

Analysis showed 0.33% H3PO4 equals 0.104% P equals 185 pyrancse units to1 HaPO4.

Mildew tests used: Metarrhizium glutinosum Duration of test: 6 days and16 days Results: Decrease in tensile strength by meterrhizium glutinosumTensile strength Original decrease tensile Strength 6 days 16 days Percent Per cent untreated 119 12 67 treated 108 0 26 Example XXX 130 partsdicyandiamide 200 parts orthophosphoric acid (75%) 200 parts water, heatto 108 C.

300 parts urea 28 parts guanidine carbonate 81,000 parts water Padded onpure cotton herringbone twill, dried, cured 5 minutes at 340 F., washedand dried.

Analysis showed 0.09% HaPO4 equals .0284% P equals 600 pyrancse units to1 H3PO4.

Mildew test used: Metarrhizium glutinosum Duration of test: 6 days and16 days Results: Decrease in tensile strength by metarrhizium glutinosumTensile Strength Original Decrease Tensile Strength 6 days 16 days Percent Per cent Untreated 119 12 67 Treated 113 5 48 Example XXXI A cottonfabric was impregnated with the following sizing mixture:

100 parts orthophosphoric acid parts urea 100 parts acetamide 1500 partswater This application is a continuation in part of application SerialNo. 596,592, filed May 29, 1945, now Patent Number 2,482,755.

We claim:

l. The process oi! imparting mildew resistance to fibrous cellulosematerial which consists in impregnating the material with an aqueoussolution of phosphoric acid and urea, the amount of solids applied tothe material being equal to that applied by a single application ofsolution with 100% solution pick-up in the weight of the material in thedry state when the solution contains from 0.2% to 4.5% acid by weight ofthe solution 10 with the urea present in the ratio of from 1 mol to 4mols to 1 mol of acid, drying the material, baking the dried material attemperatures of from 400 F. to 300 F. for from 2 to 30 minutes, andwashing and drying the material, the pH of the solution being such thatthe pH of the cured fabric before washing is from 2 pH to '7 pH asdetermined by indicator solutions, and the temperature and time selectedbeing such as to introduce ture is from 340 F. to 375 F.

3. The process of claim 1 in which the pH is from 3 to 6.

- FLORENCE M. FORD.

Name I Date Ford et al. Sept. 2'7, 1949 Number

1. THE PROCESS OF IMPARTING MILDEW RESISTANCE TO FIBROUS CELLULOSEMATERIAL WHICH CONSISTS IN IMPREGNATING THE MATERIAL WITH AN AQUEOUSSOLUTION OF PHOSPHORIC ACCID AND UREA, THE AMOUNT OF SOLIDS APPLIED TOTHE MATERIAL BEING EQUAL TO THAT APPLIED BY A SINGLE APPLICATION OFSOLUTION WITH 100% SOLUTION PICK-UP IN THE WEIGHT OF THE MATERIAL IN THEDRY STATE WHEN THE SOLUTION CONTAINS FROM 0.2% TO 4.5% ACID BY WEIGHT OFTHE SOLUTION WITH THE UREA PRESENT IN THE RATIO OF FROM 1 MOL TO 4 MOLSTO 1 MOL OF ACID, DRYING THE MATERIAL, BAKING THE DRIED MATERIAL ATTEMPERTURES OF FROM 400*F. TO 300* F. FOR FROM 2 TO 30 MINUTES, ANDWASHING AND DRYING THE MATERIAL, THE PH OF THE SOLUTION BEING SUCH THATTHE PH OF THE CURED FABRIC BEFORE WASHINGIS FROM 2 TO PH TO 7 PH ASDETERMINED BY INDICATOR SOLUTIONS, AND THE TEMPERATURE AND TIME SELECTEDBEING SUCH AS TO INTRODUCE INTO THE COMPLEX A RATIO OF ACID TO PYRANOSEUNITS OF 1 TO 20 TO 1 TO 600 IN THE WASHED DRIED MATERIAL.